Question
What is depth-first vs breadth-first?
Quick Answer
Going deep in one branch versus wide across many branches are different strategies with different costs — and the right choice depends on whether you need resolution or coverage.
Example: You are reorganizing your notes on decision-making. You could create ten top-level categories (broad/shallow) — risk, bias, heuristics, frameworks, emotions, speed, reversibility, group dynamics, consequences, meta-decisions — and drop notes loosely into each. Or you could build three deep branches — risk (subdivided into probability, exposure, tolerance, mitigation, acceptance), bias (subdivided into cognitive, social, confirmation, anchoring, survivorship), and frameworks (subdivided into expected value, regret minimization, OODA, pre-mortem, second-order). The broad version lets you find topics fast. The deep version lets you think with precision inside each topic. Neither is wrong — they solve different problems.
This concept is part of Hierarchy and Nesting in the How to Think curriculum.
Learn more in these lessons